Shunt blowout device



July 23, 1929. G. B. FULLER SHUNT BLOWOUT DEVICE Filed July 22, 1927 INVENTOR George Fa//er A T'oRNEY Patented July 23, 1929.

UNITEDv STATES PATENT OFFICE.

GEORGE B. FULLER, OF ARKONA, ONTARIO, CANADA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

SHUNT BLOWOUT DEVICE.

Application filed July 22,

The invention relates, generally, to magnetic blowout devices and especially to magnetic blowouts for switches.

In multiple-unit-train operation, it ma happen that, after the train has pulled into the yards and stopped, the third-rail shoes on one or more cars are not in contact with the third rail. Under this condition, or, if a shoe fuse happens to be out, a current of small magnitude for lighting, heating andthe operation of a compressor motor may flow through some of the bus-line switches in a direction opposite to normal. This relatively small reversed current, flowing through the few turns of a series blowout coil, lis incapable of demagnetizing the pole pieces and the core of the blowout coil after they have been magnetized by the comparatively large motor current which flows when the train is in operation. Thus, when the switch is open, there is no magnetic action present to blow the arc out and, in some cases the residual magnetism in the pole pieces and blowout core is of sullicient strength to blow the arc back into the switch-actuating mechanism. The same is true of any switch in which it is desired to `interrupt a small current after a heavy current has been passed :in the opposite direction.

The object of the invention, generally stated,`is to provide an arc-rupturing device which will be simple and reliable in operation and designed to subject an arc to a magneticblowout influence in the desired direction, regardless of the direction of flow or magnitude of the current.

A further object of this invention is to provide for maintaining an arc-rupturing field 'for a desired interval after the switch jaws have been separated. Y

Other objects of the invention will be apparent to those skilled in the art when the following description is considered. l

For a clearer understanding of the invention and the operation of its parts, reference may be had to the following description which should be read in conjunction with the accompanying drawing, in which.;

Figure 1 is a front elevation of a pneumatically operated switch showing an arrangement of blowout coils in accordance with the invention.

Fig. 2 is aside elevation of the switch,

Fig. 3 is a circuit diagram showing the connection of the Vblowout coil in accordance with the invention,

1927. Serial No. `207,590.

v Fig. 4 is a circuit diagram showing connections in a modified form of the invention,

Referring now to Figs. 1 and 2, a switch 10 y coinprisesa pair of jaws, one of which is disposed for movement to perform switching operations. The movable jaw, which is located below the other jaw. is disposed to be actuated by an' air engine 11 of any suitable type well known in the art. As shown, a magnet valve is provided for controlling the operation of the air-'engine and the lower switch jaw for transmitting motion to the latter.

An interlock member 13 is attached rigidly to the connecting vrod 14 and disposed to move vertically with it. In the embodiment illustrated, the interlock member comprises a block of insulating material on which a number of contact plates 15 are mounted. The contact plates 15 are disposed to make contact with contact lingers 16 when the switch jaws are moved into engagement. The contact plates carried by the block, are located to engage the contact fingers immediately after the initial closing movement of the lower jaw from its full-open position and are retained in engagement continuously as long as the switch remains closed.

The switch 10 is enclosed by an arcchute 17 which is disposed to confine arcs that may be drawn between the switch jaws. Iron pole pieces 18 are attached to the sides of the arcing chute 17 and serve to concentrate the magnetic flux generated when the blowout coils 19 are energized, thereby providing a desired arc-ruptuiing field. Referring now to Fig. 3, it will be seen that the blowout coil isdisposed in shunt to the switch 10. A shunt circuit around the switch 10 is completed through the contact fingers 16 and contact plates 15 immediately after the initiation of the movement of the lower switch jaw toward its closed position. In order to reduce aicing and to insure the proper duration of the arc-rupturing field when the switch is opened, the contact plates 15 and contact lingers are disposed to remain in engagement for a short interval after the initial separation of the switch jaws. A resistor Q0 is inserted in the shunt circuit and serves to limit the flow iof current through the blowout coil particularly after the switch jaws have separated and before the interlock contacts yhave separated, thereby preventing an arc from occurring at the interlock contacts. It

will be seen that, while the switch 10 is closed,

the blowout-coil circuit is short-circuited and practically no current will flow through it.

In operation, when an opening movement of the switch is initiated and the switch jaws are separated slightly, the blowout coil is eX- cited by the sudden increase of current flowing through it, and an arc-rupturing field is established. During the opening of the switch, since the jaws are disposed toV make rolling contact, the rear portions of the jaws separate first and the point of contact moves gradually toward the tip at which point an arc may be drawn.. Then an arc is drawn at the tip itis forced outward and lengthened through the action of the blowout field on the field surrounding the arc.

It will be readily understood that this magnetic blowout action is effective, irrespective of the direction the currentflows through the' switch, since, with a reversal ofthe main current-,- a reversal of its field occurs and, simultaneously,a'reversal of the blowout field occurs. In addition to being subjected to a magnetic blowout action, the arc is confined within the arcing chute.

In the use of shunt blowout coils, it is possible to provide a sufiicient number of turns in the coil to effectively magnetize the pole piece with a very small current. It will also be seen that, as thejaws separate and the arc is drawn out, the resistance of this path increases so that a greater current will flow through the shunt blowout coil and thereby develop an increasing arc-rupturing field.

However, t-he resistor 20, connected in series with the blowout coil will prevent the current from increasing to such magnitude as to cause arcing at the interlock contact plates when the blowout-coil circuit is broken.

In Fig. 4, a compoundcoil arrangement is shown. The operation in this case is similar to that described, hereinbefore and the series coil serves to boost the strength of the blowout field established by the shunt blowout coil.

Since the application of this invention is vnot limited to the type of switch described, it is desired that'the embodiment described hereinbefore be considered illustrative an-d not in a limiting sense. i

I claim a-s my invention:

1. In a circuit-interrupting device, in combination, a switch,arc-rupturing means provided with a blowout coil associated with the switch, a circuit for shunting the switch, said blowout coil being connected in the shunt circuit, andan interlock disposed to control the shunt circuit, said interlock being disposedto maintain the shunt circuit closed after the initial opening of the switch. Y

2. In a-.circuit-interrupting device, in comf bin'ation, aswitch, arc-rupturing means provided with a'blowout coil associa-ted4 with theY switch, means for maintaining a magnetic blowout field for an interval after the separat-ion of the switch aws, a circuit for shunting the switch comprising the blowout coil, a resistor and an interlock for controlling the circuit. f

3. In a circuit-interrupting device, in combination, a switch, arc-rupturing means provided with a blowout coil associated with the switch, a circuit for sliunting `the switch, said blowoutcoil being connected in the shunt circuit, means for limiting the flow of current through the shunt circuit and an interlock disposed to control the shunt circuit, said interlock being disposed'for the operaton with the switchl and to maintain the shunt circuit closed after the initial opening of the switch.

.4. In a circuit-interrupting device, in combination, a switch, arc-rupturing means provided with a blowout coil associated with the switch, a circuit for shunting the switch, said blowout coil being connected in the shunt circuit, an interlock disposed to control the'shunt circuit and a resistor connected in series with the blowout coil in the shunt circuit, said resistor disposed to limit the flow of current in the shuntcircuit and reduce arcing atthe interlock contact.

5. In a circuitinterrupting device, in combination, a switch,`arcrupturing means provided with a blowout coil associated with the switch, a circuit Jfor shunting the switch, said blowout coil being connected in the Vshunt circuit, means'for limiting the flow of current through the shunt circuit and an interlock Adisposedto control the shunt circuit, said interlock comprising an insulating block disposed to be actuatedY by the switch, said switch giving vertical motion to the insulating block, when operated, a plurality of contact plates j attached tothe insulating block, a plurality of contact fin Gers disposed to engage the contact plates, suchh engagement existing while the switch .is closed and continuing for a predetermined interval after separation of the switch j aws.

6. In a circuit-interrupting device, aswitch, arc-rupturing means provided with a blowout coil, said blowout Vcoil being connected in Vparallel-circuit relation tothe switch, and interlocking contact members operated by the switch for controlling the energization of' the blowout: coil, said interlocking contact members 'disposed to remain in their circuit-closing ing of the switch, whereby an arc-rupturing field is maintained after the operation ofthe switch.

In testimony whereof, I have hereunto subscribed my name this 11th day of July, 1927.

' GEORGE B. FULLER. 

